const Topic = require('../models/topics')
const User = require('../models/users')
const Question = require('../models/questions')

class TopicsCtl {
  async find (ctx) {
    const page = Math.max((ctx.query.page || 1) * 1, 1) - 1
    const perPage = Math.max((ctx.query.per_page || 2) * 1, 1)
    ctx.body = await Topic.find({ name: new RegExp(ctx.query.q) }).limit(perPage).skip(page * perPage)
  }
  async checkTopicExist (ctx, next) {
    const topic = await Topic.findById(ctx.params.id)
    if (!topic) {
      ctx.throw(404, '话题不存在！')
    }
    await next()
  }
  async findById (ctx) {
    const { fields = '' } = ctx.query
    const selectFields = fields.split(';').filter(f => f).map(f => '+' + f).join('')
    const topic = await Topic.findById(ctx.params.id).select(selectFields)
    ctx.body = topic
  }
  async create (ctx) {
    ctx.verifyParams({
      name: { type: 'string', required: true },
      avatar_url: { type: 'string', required: false },
      introduction: { type: 'string', required: false }
    })
    const topic = await new Topic(ctx.request.body).save()
    ctx.body = topic
  }
  async update (ctx) {
    ctx.verifyParams({
      name: { type: 'string', required: false },
      avatar_url: { type: 'string', required: false },
      introduction: { type: 'string', required: false }
    })
    const topic = await Topic.findByIdAndUpdate(ctx.params.id, ctx.request.body)
    ctx.body = topic
  }
  async listFollowers (ctx) {
    const users = await User.find({ followingTopics: ctx.params.id })
    ctx.body = users
  }
  async listQuestions (ctx) {
    const questions = await Question.find({ topics: ctx.params.id })
    ctx.body = questions
  }
}

module.exports = new TopicsCtl()